... over-medium diameter,such as,Tower Crane,Truck crane,and so on.3. Single-Row Crossed Roller Slewing Ring( 11 series) The Single ... -Row Crossed Roller Slewing Ring is composed of ... ,Welding Operation Machine,Pint-size&Medium-sized Crane,and so on.6. Single-Row Crossed Roller Slewing Ring( HJ series) The Single ...